Receive the latest national-international updates in your inbox

FILE - Then-Trump campaign chairman Paul Manafort talks to reporters on the floor of the Republican National Convention at Quicken Loans Arena, July 17, 2016, in Cleveland.

Shortly before Donald Trump secured the Republican nomination last summer, his campaign chairman offered to provide private briefings on the race to a Russian billionaire with Kremlin ties, his spokesman confirmed to NBC News.

The offer appeared in emails between then campaign chairman Paul Manafort and one of his employees, some of which suggested Manafort was seeking to use his role to make money, the Washington Post reported. The spokesman, Jason Maloni, said the emails, which had been turned over to congressional committees, showed nothing improper.

The Post said the billionaire was Oleg Deripaska, an oligarch in Putin's inner circle. NBC News has reported that Manafort had business dealings with Deripaska, who was once denied entry to the United States because of alleged mafia links.

"If he needs private briefings we can accommodate," Manafort wrote in the July 7, 2016, email, the Post reported.